Proton decay from the isoscalar giant dipole resonance in $^{58}$Ni

TL;DR

This study measures proton decay from the isoscalar giant dipole resonance in nickel-58, revealing detailed decay properties and structural differences as a function of excitation energy, and compares results with theoretical predictions.

Contribution

It provides new experimental data on proton decay branching ratios from the ISGDR in $^{58}$Ni and compares these with recent continuum-RPA calculations.

Findings

Proton decay branching ratios to low-lying states in $^{57}$Co were determined.

Differences in ISGDR structure were observed as a function of excitation energy.

Experimental results show good agreement with theoretical predictions in certain energy regions.

Abstract

Proton decay from the 3$\hbar\omega$ isoscalar giant dipole resonance (ISGDR) in $^{58}$Ni has been measured using the ($\alpha,\alpha'p$) reaction at a bombarding energy of 386 MeV to investigate its decay properties. We have extracted the ISGDR strength under the coincidence condition between inelastically scattered $\alpha$ particles at forward angles and decay protons emitted at backward angles. Branching ratios for proton decay to low-lying states of $^{57}$Co have been determined, and the results compared to predictions of recent continuum-RPA calculations. The final-state spectra of protons decaying to the low-lying states in $^{57}$Co were analyzed for a more detailed understanding of the structure of the ISGDR. It is found that there are differences in the structure of the ISGDR as a function of excitation energy.